Biomedical subjects

G Galbariggi

Publications and source records attributed to G Galbariggi.

4 recordsLinked to original sources

PubMed1992

Norepinephrine-induced plasma dopamine decrease in man: pharmacological evidence of the involvement of alpha 2-adrenoceptors.

OBJECTIVE: The purposes of this study were: (1) to test whether intravenous infusion of norepinephrine can affect plasma dopamine levels; and (2) to explore to what extent dopamine-2 or alpha 2-receptors play a role in this response. DESIGN: Norepinephrine infusion in man was performed to test whether the increase in norepinephrine during sympathetic stimulation can affect dopamine release. Specific antagonists of presynaptic dopamine-2 and alpha 2-receptors were administered to test the receptor(s) involved in this possible regulatory phenomenon. METHODS: Plasma catecholamine levels were investigated in seven normal subjects before and after administration of domperidone (dopamine-2 antagonist), yohimbine (alpha 2-antagonist) and norepinephrine. RESULTS: Both oral domperidone and yohimbine induced a significant increase in both plasma norepinephrine and plasma dopamine. Norepinephrine infusion induced a significant decrease in plasma dopamine. Pretreatment with domperidone only partially counteracted this inhibitory effect of norepinephrine infusion, whereas yohimbine fully counteracted it. CONCLUSIONS: Our data show that norepinephrine may act as a hormone at plasma concentrations as low as 450 pg/ml. The norepinephrine-induced plasma dopamine decrease seems to be alpha 2-adrenoceptor-mediated. This norepinephrine effect may be involved in the physiologic decrease in plasma dopamine that we demonstrated in the upright position in normal subjects.

Administration, Oral↗

PubMed1991

Absence of correlations between plasma catecholamine levels and mononuclear leukocyte beta 2-adrenergic receptors in the elderly.

To assess the effects of aging on catecholamine plasma levels and mononuclear leukocyte (NML) beta 2-adrenergic receptors and on the possible relationships between these two parameters, we evaluated two groups of human subjects: 18 elderly volunteers (age 65-70 years) and 13 young volunteers (age 21-35 years). Norepinephrine plasma levels were significantly higher in the elderly subjects compared to the younger ones (P less than 0.05), whereas plasma epinephrine levels were not different. Also MNL beta 2-adrenoceptor density was significantly higher in elderly subjects (P less than 0.05). The binding dissociation constants were not significantly different. In young subjects there was a significant (P less than 0.02), inverse relationship between receptor densities and plasma norepinephrine levels; this relationship was not present in elderly persons. Our data suggest that the increase in beta 2-adrenoceptors may be due to a compensatory phenomenon, owing to the reduced beta-adrenergic sensitivity observed in the elderly subjects; moreover, the regulation of beta-adrenoceptors by plasma catecholamines seems to be altered by aging.

Adult↗

PubMed1991

Intraindividual variation of beta 2-adrenergic receptors on mononuclear leukocytes and their relationships with endogenous plasma catecholamines in man.

The interindividual and intraindividual variations of both MNL beta 2-adrenergic receptor density and dissociation constant of binding were evaluated in 19 healthy volunteers. In addition the possible relationships between catecholamine plasma levels and MNL beta 2-adrenergic receptor density were studied in 8 of these subjects. The volunteers were studied three times with ten days' interval. There was a significant inverse relationship between receptor density and norepinephrine plasma levels, only. Neither epinephrine nor dopamine were correlated with receptor density. Interindividual coefficient of variation was 29.57%. The mean value of the intraindividual coefficients of variation was 14.1%, while the mean value of the analytical coefficients of variation was 10%. Our results are at some variance with data in the literature and may contribute to elucidate the role of MNL beta 2-adrenergic receptors as an index of sympathetic function in man.

Adult↗

PubMed1991

Comparative effects of long-term therapy with captopril and ibopamine in chronic congestive heart failure in old patients.

Little is known concerning the long-term drug management of chronic heart failure (CHF) in old patients (greater than or equal to 75 years). Accordingly, this double-blind, placebo-controlled trial compared the long-term (over 6 months) effect of captopril (37.5-75 mg/day) and of ibopamine (150-300 mg/day) on exercise testing, symptoms and subjective feeling of well-being, in 150 CHF elderly patients (mean age 75 years) under treatment with digitalis and/or diuretics. During an additional open follow-up of approximately 1.5 years, morbid events and deaths were also recorded. Captopril and ibopamine performed better (p less than 0.01) than placebo, improving the 6-min walking distance (captopril from 300 to 404 m, ibopamine from 282 to 385 m; placebo from 283 to 299 m). NYHA status, symptom score and patients' global assessment. The difference between the active study drugs was not statistically significant (p greater than 0.05). Complicating events, including diuretic use, frequency of hospitalization, worsening of CHF and deaths, were grouped by patient-years. These events were significantly (p less than 0.01) lower (captopril: 28/75 patient-years; ibopamine 33/74 patient-years) in the active treatment groups with respect to placebo (58/96 patient-years). Captopril and ibopamine showed a different safety profile. Creatinine increase (2 patients), symptomatic hypotension (4 patients), hyperkalemia (2 patients) and upper respiratory symptoms were mostly associated with captopril treatment. Gastrointestinal adverse events were observed in 11 patients under ibopamine treatment. The study provides evidence of the clinical usefulness of both captopril or ibopamine in the long-term treatment of CHF in old patients. The safety profile of each drug will suggest the preferred therapeutic application.

Aged↗